Determining services accessible via a subscription in a communication system

ABSTRACT

A method, a system and a network node for determining services accessible via a subscription having an account and at least a first limit in a communication system. The method includes defining at least a first set of services and a second set of services to be used with the subscription, each set of services defining services accessible via the subscription, comparing the balance of the account with the first limit, using the first set of services when the balance of the account does not reach the first limit, and using the second set of services when the balance reaches the first limit.

This is a National Stage application of International Application No.PCT/FI01/00688, which was filed on Jul. 31, 2001, which designated theU.S., and was filed in the English language.

BACKGROUND OF THE INVENTION

The invention relates to services accessible via a subscription in acommunication system, and particularly to a subscription having anaccount and a predetermined limit. Examples of such subscriptions are aprepaid subscription and a postpaid subscription with a limit indicatingthe maximum allowed amount to be billed. A postpaid subscription refersto a subscription which is charged in arrears.

Mobile communications systems have been developed in order to freepeople from fixed telephone terminals without hindering theirreachability. Often the mobile communications network is an accessnetwork providing a user with wireless access to external networks,hosts, or services offered by specific service providers. Thedevelopment of packet-switched services, such as the General PacketRadio Service GPRS in the Pan-European mobile communications system GSM(Global System for Mobile Communications), allowing packet datatransmission between mobile data terminals and external data networks,enables the development of a variety of services. One example of suchservices are different WAP (Wireless access protocol) services via whichservice providers can provide services free of charge, i.e. services theusage of which is paid by the service provider and/or an advertiser.

Along with the mobile communications systems, a variety of servicesprovided through mobile stations have also been developed. One exampleof new services becoming increasingly popular is a prepaid subscription.The prepaid subscription involves no billing in arrears but the accountof the prepaid subscription is charged in real-time during calls. Theprepaid subscription can usually be used for chargeable connections orservices until the credit in the subscription's account runs out, inother words until the prepaid amount has been exhausted. Another servicesimilar to the prepaid service is a postpaid service with a limitedbill, i.e. a postpaid subscription with a limit indicating the maximumallowed amount to be billed. It differs from the prepaid subscription inthat the subscription allows access to chargeable connections orservices until the bill reaches the limit.

Both of these services are expected to be widely popular also for packetswitched services. The problem related to the arrangement describedabove is that when the subscription does not allow access to chargeablecalls, it does not allow access to services free of charge either. Theprepaid subscription involves another problem, too. Usually, thesubscriber to the prepaid subscription, or someone else, can depositmore money in the subscription's account. However, when the prepaidamount has been exhausted, money can not be deposited via the prepaidsubscription.

BRIEF DESCRIPTION OF THE INVENTION

An object of the invention is to provide a method and an apparatusimplementing the method to eliminate the above-mentioned problems. Theobjects are achieved with a method, a system and a network node whichare characterized in what is disclosed in the independent claims. Thepreferred embodiments of the invention are set forth in the dependentclaims.

The invention is based on defining at least two sets of services for thesubscription having an account with a predetermined limit, one set ofservices being used when the predetermined limit has not been reachedand the other when the predetermined limit has been reached. The latterset of services preferably comprises services free of charge. The mostimportant advantage of the invention is that it provides access tocertain services even when the subscription can not be used forconnections or services to be charged from the subscription.

In a preferred embodiment of the invention the sets of services aredefined for a prepaid service and at least the second set of servicescomprises a depositing service. This has the advantage that the user candeposit money in his prepaid account also when the balance of theprepaid account has been used. Furthermore, this is a very convenientway to deposit money in one's prepaid account.

In one embodiment of the invention in response to the second set ofservices the user is informed of the services accessible via the secondset of services. This has the advantage that the user knows for what hecan use his subscription. He may even receive information how to renewthe subscription and/or how to use some other service(s) available.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be described in greater detail by means of preferredembodiments with reference to the accompanying figures, in which

FIG. 1 is a simplified block diagram of a system providing the GPRS;

FIG. 2 is a flow chart illustrating the functionality of an SCP in afirst preferred embodiment of the invention;

FIG. 3 is a signalling chart illustrating a second preferred embodimentof the invention;

FIG. 4 is a signalling chart illustrating the signalling according tothe first preferred embodiment of the invention; and

FIG. 5 is a flow chart of a depositing service in the first preferredembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is applicable to any system providing prepaidsubscriptions and/or postpaid subscriptions with limited bills. Thepresent invention is particularly well applicable to any packet switchedsystem in which an individual packet data address is activated as in theGPRS service before it can be used. These systems include the‘third-generation mobile communication systems’, such as the UniversalMobile Telecommunications System (UMTS) and IS-41 (Interim Standard),mobile communication systems corresponding to the GSM system, such asthe DCS 1800 (Digital Cellular System for 188 MHz) and PCS (PersonalCommunication System), and WLL systems which are based on theabove-mentioned systems and implement a GPRS-type packet radio.Furthermore, the invention can be applied in systems other than mobilecommunication systems, such as cable modem networks and similar fixedsystems. The invention will be described in the following using the GPRSservice of the GSM system as an example, but the invention is notlimited to such a system. The definitions of mobile communicationsystems evolve rapidly, which may necessitate additional changes to theinvention. For this reason, all the terms and expressions should beinterpreted broadly, and it should also be kept in mind that they areonly intended to describe the invention, not to limit it. For example,in IP networks there are policy repository points and policy decisionpoints in which the functions described later can be implemented insteadof HLRs and SCPs. The function is essential for the invention, not thenetwork node in which the function is located.

FIG. 1 shows a simplified network architecture according to a firstpreferred embodiment of the invention, describing only some of theelements of a system architecture. The network nodes illustrated in FIG.1 are logical units, the implementation of which may differ from the onedescribed. It is obvious to one skilled in the art that the system mayalso comprise other functions and structures which need not to bedescribed in closer detail here.

FIG. 1 illustrates the network architecture of a GPRS service Saccording to the first preferred embodiment of the invention at ageneral level because a more detailed structure of the network isirrelevant to the invention. The structure and function of the GSMsystem are very familiar to a person skilled in the art. The structureof the GPRS service is defined e.g. in ETSI specification 03.60, version6.0.0 (Digital cellular telecommunications system (Phase 2+); GeneralPacket Radio Service (GPRS); Service Description; Stage 2), which isincorporated herein by reference. The GPRS service comprises an accessnetwork which provides radio access and is represented by the basestation subsystem BSS of the GSM system in FIG. 1. In the thirdgeneration (3G) mobile communications systems, such as the UniversalMobile Telecommunications System (UMTS), the access network is RadioAccess Network (RAN), whereas the GPRS network is a core network (CN)connected to the RAN. The GPRS service also comprises, as edge nodes,support nodes of the GPRS service for packet switched transmission ofdata between a packet data network and a mobile station MS. The supportnodes include a serving GPRS support node SGSN and a gateway GPRSsupport node GGSN. These support nodes SGSN and GGSN are interconnectedby a backbone network 1. It should be noted that the functionalities ofthe SGSN and the GGSN can also be physically combined into the samenetwork node, in which case the operator's backbone network isunnecessary. Logically the nodes are, however, separate nodes.

The GPRS interface comprises for a mobile station MS one or moreindividual PDP (packet data protocol) contexts which describe the packetdata address the MS can use to send and receive data packets when thePDP context is active. Thus the PDP context can be seen as a connection.The PDP context defines different data transmission parameters, such asthe PDP type (e.g. X.25 or IP), PDP address (e.g. IP address), qualityof service QoS, access point name APN and NSAPI (Network Service AccessPoint Identifier). The APN of the PDP context is used by the SGSN toselect the appropriate GGSN (supporting this specific APN). The APNconfiguration in the GGSN defines where and how to connect the user ofthe PDP context. Thus the APN can be used to define a set of services. Acertain level of security (e.g. is password required or not), a certainway to collect charging information, a certain address range, etc. canbe linked to the APN. The billing system can also be configured to billdifferent APNs differently. In the first and second preferred embodimentof the invention the different sets of services are defined by usingdifferent APNs, as described later.

The serving GPRS support node SGSN serves the mobile station MS. Eachsupport node SGSN produces a packet data service for mobile dataterminals, i.e. mobile stations MS, within the area of one or more cellsin a cellular packet radio network. For this purpose, each support nodeSGSN is typically connected to the GSM mobile communication system(typically to the base station controller in the base station subsystemBSS) so that the intermediate mobile communication network providesradio access and packet switched data transmission between the SGSN andthe mobile stations. In other words, the mobile station MS in a cellcommunicates with a base station over the radio interface and furtherthrough the base station subsystem with the support node SGSN to theservice area of which the cell belongs. The main functions of the SGSNnode are to detect new GPRS mobile stations in its service area, tocarry out registration of new mobile stations MS together with GPRSregisters, to send data packets to or to receive them from the GPRSmobile station and to maintain a file on the location of the mobilestations MS within its service area. This means that the SGSN performssecurity functions and access control, such as authentication andencryption procedures and determination of the APN(s) this mobilestation is allowed to access. The SGSN can participate in collecting thebilling information. The SGSN according to the first and secondpreferred embodiment of the invention comprises a function similar tothe service switching function in the intelligent network. In otherwords, the SGSN functions as a service switching point SSP of theintelligent network.

The GPRS gateway support nodes GGSN connect the operator's GPRS networkto the external systems, data networks, such as an IP network (Internet)or an X.25 network, and servers. The GGSN can also be directly connectedto a private company network or to a host. In the example of FIG. 1, theGGSN is connected to the servers 2 via the Internet network 3 and to theInternet network 3 via a firewall FW. It should be understood that otherkind of connections are also possible. The GGSN comprises GPRSsubscribers' PDP contexts and routing information, i.e. the SGSNaddresses. The GGSN functions as a router between an external addressand internal routing information (e.g. SGSN). The GGSN may also transmitpackets from one mobile station to another within the network. Inaddition, the GGSN is responsible for billing of data traffic.

The firewall FW configuration can apply a specific screening policy to acertain address range, that is to a certain APN. For example, thescreening policy can restrict access of certain application, restrictestablishment of an IP connection from certain addresses and/or restrictsending/receiving packets to/from certain address.

The mobile station MS may be any mobile node which supports packet datatransmission and has a radio interface to the network. It can be, forexample, a laptop PC which is connected to a cellular phone capable ofpacket radio operation, or an integrated combination of a small computerand a packet radio phone. The other embodiments of the mobile station MSinclude various pagers, remote-controllers, monitoring and/or dataacquisition devices, etc. The mobile station may also be called a mobilenode or a mobile host. The mobile station MS comprises an actual mobileequipment ME and a detachably connected identification card SIM, alsocalled a subscriber identity module. In this context, a mobile stationMS generally means the entity formed by the SIM card and the actualmobile equipment. The SIM card is a smart card that holds the subscriberidentity, performs authentication algorithms, and stores authenticationand encryption keys and some subscription information that is needed inthe mobile station. The mobile equipment ME is the radio terminal usedfor radio communication over the radio interface.

Subscription data on each subscription of the network is storedpermanently or semi-permanently in a home location register HLR in sucha manner that the subscription data is connected to the subscriber'sidentifier IMSI. The subscription data includes routing information,i.e. the current location of the subscriber, and information on theservices the subscriber can access. The subscription data also includesinformation on the subscribed APNs.

In the first and second preferred embodiment of the invention twodifferent kind of servers 2 are used in order to restrict access toservices free of charge. In the first preferred embodiment chargeableservices are provided via a server WAP1 and services free of charge areprovided via a server WAP2. An example of a free of charge WAP serviceis a depositing service, which allows to deposit money in the prepaidaccount. The depositing service is described in greater detail with FIG.5. Another example is an advertisement, for example a map showing thelocation of the nearest McDonalds restaurant.

In the first preferred embodiment of the invention illustrated in FIG.1, it is assumed that the prepaid service is implemented as anintelligent network service. In association with an intelligent networkservice, a service program is started at the service control point SCP,the operation of the program determining the messages transmitted by theSCP to the SSP at each stage of a call. In a prepaid service, eachprepaid subscription has its own account the balance of which is reducedduring an ongoing call charged from the subscription. The balance of theaccount is updated and monitored usually in the SCP. In the GPRS the SCPis usually a CAMEL (Customised Applications for Mobile network EnhancedLogic) Service Environment. The CAMEL is, like the GPRS, also a GSM 2+phase service. The functionality of the SCP according to the firstpreferred embodiment is described in greater detail with FIG. 2.

In the second preferred embodiment of the invention it is also assumedthat the prepaid service is implemented as an intelligent networkservice. In the second preferred embodiment of the invention (not shownin FIG. 1) the SCP is also connected to the HLR in order to enable theSCP to modify the subscription data, for example the subscribed APN. Thefunctionality of the SCP according to the second preferred embodiment isdescribed in greater detail with FIG. 3.

In the example illustrated in FIG. 1, the prepaid subscriptioninformation, including the balance of the account, is in a databaselocated in a service management point SMP. The SMP may also monitor andupdate the balance of the account during an ongoing call. When thebalance is monitored in some other network node, the network nodemonitoring the balance (usually the SCP) updates the balance of thesubscription during an ongoing call. Alternatively, the prepaidsubscription information may be located in different databases and/or insome other network element, such as the home location register HLR or aseparate prepaid server.

In addition to means required to implement the prepaid service and/orpostpaid service with a limited bill according to the prior art, thetelecommunications system implementing the functionality of the presentinvention also comprises means for maintaining at least two differentsets of services, means for comparing the balance of the account to apredefined limit and means for selecting the set of services to be usedon the basis of the comparison. Current network nodes compriseprocessors and memory, which can be utilized in the functions of theinvention. All changes required for implementing the invention can becarried out as added or updated software routines and/or withapplication circuits (ASIC).

FIGS. 2 and 4 illustrate the first preferred embodiment of the inventionand FIG. 3 illustrates the second preferred embodiment of the invention.In the examples illustrated in FIGS. 2, 3 and 4 it is assumed that thesubscription is a prepaid subscription in which the preset minimumbalance of the account is zero. When the balance is the minimum balance,only a set of services free of charge is allowed in the first and secondpreferred embodiment of the invention. The set includes emergency calls.

In the first and second preferred embodiment of the invention thedifferent sets of services are defined by using different APNs. In thefirst and second embodiment of the invention the first set of servicescomprises both services charged from the subscription and services freeof charge including the depositing service, and the second set ofservices comprises only the services free of charge including thedepositing service. Thus the second set of services is a subset of thefirst set of services. The first set of services is used when thebalance of the account has not reached the minimum balance. For thefirst set of services a first APN is configured into the GGSN and forthe second set of services a second APN is configured into the GGSN. Thefirst APN which provides access to the first set of services allowsaccess to both WAP servers, WAP1 and WAP2, illustrated in FIG. 1. Thesecond APN which provides access to the second set of services allowsaccess only to the server providing services free of charge (i.e. WAP2in FIG. 1). This can be implemented by applying a restrictive screeningpolicy in the firewall to the range of address allocated to the secondAPN, for example.

FIG. 2 is a flowchart representing the functionality of the SCPaccording to the invention in the first preferred embodiment. For thesake of clarity it is assumed that the APN which is selected can beaccepted. In the first preferred embodiment of the invention the firstAPN is stored in subscription information in the HLR as the subscribedAPN and the second APN is common to all prepaid subscribers and storedin the SCP.

In FIG. 2 the SCP receives an inquiry from an SGSN concerning a prepaidsubscription, in step 201. The inquiry is triggered by ‘attach request’or ‘PDP context activation request’, for example. In response to theinquiry the SCP obtains, in step 202, the balance of the account for thesubscription and the predefined limit, which is the preset minimum valuein the first preferred embodiment of the invention. In step 203, the SCPchecks whether the balance exceeds the limit. In other words, the SCPchecks whether has the balance has reached the limit. If the balanceexceeds the limit (step 203), the SCP indicates in its response, in step204, that the first set of services is used. In other words, the SCPindicates that the first APN is used. In the first preferred embodimentof the invention this indication is a normal response (i.e. ‘continuenormally’) to the inquiry, and the SGSN interprets this to mean the APNwhich is in the subscription information in the HLR, i.e. the first APN.

The SCP monitors the balance of the account when the PDP context (andthe set of services used) allows services charged from the subscription.When the balance of the prepaid account reaches the limit (step 205) atwhich services charged from the subscription are no longer allowed, theSCP triggers (step 206) the deactivation of the PDP context in the firstpreferred embodiment of the invention. This deactivation may comprise amessage sent by the WAP server to the mobile station, the messageinforming the user the balance has reached the limit and recommendingthe user to deposit money in the account. At the same time the SCPreduces the quality of the service QoS in order to minimize the costs inthe first preferred embodiment of the invention.

If the balance does not exceed the limit (step 203), the SCP indicatesin its response in step 207 that the second set of services are used. Inother words the SCP indicates that the second APN is used. In the firstpreferred embodiment of the invention the SCP sends in response to theinquiry the name of the second APN to be used in step 207. This secondAPN overrules the subscribed APN if the subscribed APN is something elsethan a wildcard. (Wildcard means that any APN is acceptable.) If themobile station has requested an APN, it is overruled by the second APN.In the first preferred embodiment of the invention the second APN isconfigured in the SCP and it is common to all prepaid subscribers usinga prepaid service of this service provider.

In embodiments where the SCP sends the name of the APN to be used instep 207 in the response to the inquiry received in step 201, the APNdefinitions may, instead of being in the SCP, be in subscriptioninformation maintained either in the home location register HLR or inthe service management point SMP or in a corresponding network nodewhere information concerning the prepaid subscription is maintained. Inthese embodiments it is also possible that the second APN issubscriber-specific. In these embodiments the SCP receives the secondAPN as part of the subscriber information regardless of whether thesecond APN is common to all subscribers or subscriber-specific.

In some other embodiment of the invention the SCP may send the name ofthe first APN to the SGSN in step 204. This APN then overrules the APNin subscriber information and/or requested by the mobile station.

In some other embodiment of the invention the message sent in step 204includes an explicit indication indicating that chargeable services areallowed and the SGSN then selects the APN according to the prior art.

In some other embodiment of the invention the SCP may in step 207 send,instead of the name of the second APN, an indication to the SGSNindicating that only services free of charge are allowed. Thisindication can be the message itself, i.e. the SGSN receives a replyfrom the SCP that calls are not allowed and the SGSN interprets this tomean the second APN. In this embodiment the second APN is eitherpreconfigured to the SGSN or the SGSN has means to find it, for exampleby requesting it from the HLR or from the SMP.

In some other embodiments of the invention the set of services which canbe used is indicated with the charging characteristics to be applied.The charging characteristics indicate to the SGSN how to collectcharging information. For example, when the charging characteristics is‘not collect charging information’, it is interpreted to mean that thesubscriber is allowed to use only services free of charge.Correspondingly, the charging characteristics indicating ‘collectcharging information’, is interpreted to mean that the subscriber isalso allowed to use chargeable services, i.e. the first set of services.In these embodiments the first and/or second APN can be preconfigured tothe SGSN or the SGSN has means to find them (or the other ones notpreconfigured in the SGSN), for example in the HLR or in the SMP.

In some embodiments of the invention a set of limits is defined for theprepaid account, one limit being the limit after which only servicesfree of charge are allowed. In the embodiments the SCP monitors alllimits after step 204. Some limits may trigger sending of a specialmessage to the mobile station MS. One example is a message sent by theWAP server to the mobile station, the message informing the user thatthe balance will soon reach the limit and recommending the user todeposit money in the account. Some limits may trigger changes to theaccess rights, such as reduction of the QoS in order to minimize thecosts. The SCP can take care of the reduction or the HLR takes care ofthe reduction after receiving a triggering impulse from the SCP.

FIG. 3 illustrates the functionality of the SCP in the second preferredembodiment of the invention in a situation where the PDP context hasbeen established with the first set of services. In other words, themobile station has access to services charged from the prepaid account.

In the second preferred embodiment of the invention the SCP is connectedto the HLR. In the second preferred embodiment of the invention thereare two different APNs in the subscriber information in the HLR, one ofthem being the first APN allowing also access to chargeable services andthe other one the second APN allowing access only to services free ofcharge. In the second preferred embodiment of the invention the HLR alsocontains a flag, for example, which indicates which one of these twoAPNs is the allowed APN, i.e. the subscribed APN. Thus the HLR has thefirst and second APN preconfigured for this subscriber, and is ready touse one of them as the allowed APN in the subscriber information sent tothe SGSN, for example. In the second preferred embodiment of theinvention the SCP takes care of this flag. When the balance of theaccount exceeds the limit, the first APN is the allowed APN, and whenthe balance does not exceed the limit, the second APN is the allowedAPN. The HLR sends the allowed APN to the SGSN as part of thesubscription information.

Referring to FIG. 3, the SCP monitors the balance in point 3-1 until itreaches the preset minimum value. When the balance reaches the minimumvalue, the SCP sends an instruction to set the second APN as the allowedAPN to the HLR in message 3-2. The instruction may contain the name ofthe second APN and/or an indication indicating that only services freeof charge are allowed.

In response to message 3-2 the HLR sets the second APN as the allowedAPN. In other words, the HLR modifies the subscription information inpoint 3-3. In response to modifying the subscription information the HLRsends, according to the prior art, message 3-4 to the SGSN in order tomodify the subscription data stored in the SGSN. In response to message3-4 the SGSN notices that an active PDP context was activated withsubscription information which is not valid anymore and, according tothe prior art, triggers the deactivation of the PDP context in point3-5.

When the mobile station MS reactivates its PDP context next time, it isconnected to the second APN (assuming that the MS always requests thesubscribed APN, i.e. no APN is configured in the MS.)

Similarly, when some money is added to the account, the SCP sends aninstruction to the HLR to set the first APN as the allowed APN. Thisinstruction triggers the deactivation procedure and as a result of thereactivation after the latter deactivation, that the MS will beconnected to the first APN.

In one embodiment of the invention the subscription information in theHLR includes only the allowed APN. In this embodiment, the instructionsent from the SCP (e.g. message 3-2) contains the name (or otheridentity or a wildcard) of the APN to be used as the allowed APN and theHLR replaces the name in the subscription information with the nameincluded in the instruction.

In some other embodiments of the invention some other entity maintainingthe balance, such as the SMP or a prepaid server, will ensure that theHLR knows which APN is the allowed APN, i.e. the subscribed APN.

FIG. 4 illustrates the activation of the PDP context initiated by themobile station in the first preferred embodiment of the invention in asituation where the balance of the prepaid account has reached thepreset minimum value and only services free of charge are available. ThePDP context can be activated when the mobile station attaches to theGPRS network. Alternatively, the mobile station may activate the PDPcontext later or activation may be performed as a result of anactivation request received from the GPRS network (GPRS networkrequested PDP context activation). The PDP context is created using aGTP protocol (GPRS Tunnelling Protocol).

In FIG. 4 it is assumed for the sake of clarity that the mobile stationhas made its presence known to the network by carrying out a GPRS attachoperation. When the mobile station MS attaches to the GPRS network (in aGPRS attach procedure), the SGSN creates a mobility management context(MM context) and a logical link LLC (Logical Link Control) isestablished between the mobile station MS and the SGSN node in aprotocol layer. The MM context is stored in the SGSN node and mobilestation MS. The MM context of the SGSN node may contain subscriber data,such as the subscriber's IMSI, TLLI (Temporary Logical Link Identifier)and location and routing information, etc.

Referring to FIG. 4, the mobile station MS activates the PDP context bysending message 4-1 (Activate PDP Context Request) to the SGSN. Inmessage 4-1 the mobile station provides information on the TLLI, PDPtype, requested QoS and NSAPI, and optionally on the PDP address andaccess point name APN. With messages 4-2 the MS and the SGSN executesecurity functions, such as authentication of the subscriber using thesubscription.

Since the subscription is a prepaid subscription, the SGSN encounters asubscription-specific trigger (detection point) in point 4-3, as aresult of which it requests context processing instructions from the SCPin message 4-4.

In point 4-5, the SCP checks the balance of the prepaid account. Sincein the example illustrated in FIG. 4 the balance has reached the presetminimum value, the SCP sends instructions to use the second APN inmessage 4-6. In the first preferred embodiment of the invention the SCPsends the name of the second APN. In message 4-6, in the first preferredembodiment the SCP sends, in addition to the second APN, the chargingcharacteristics to be applied. The charging information will further betransmitted to the GGSN and Charging Gateway. The SCP may also returnother information such as which GGSN PLMN to select for the connection(e.g. a home PLMN, a visited PLMN, etc.). By controlling the selectionof the network of the GGSN the SCP can make sure that the set ofservices is the one it ought to be; since the APN defines a set ofconfiguration in a given GGSN and if many operators use the same APN,they may not have exactly the same configuration. (The configurationdefines allowed services.)

The SGSN sends message 4-7 (Create PDP Context) to the GGSN node, themessage 4-7 including the name of the second APN and an indicationindicating that the APN to be used is the second APN. In other words,the message 4-7 indicates to the GGSN that the APN allowing access onlyto services free of charge is used with this PDP context. Afterreceiving the message 4-7, the GGSN creates the PDP context in point 3-8and sends it to the SGSN in message 4-9 (Create PDP Context response).The GGSN is in the first preferred embodiment configured to send message4-10 to a WAP server of the system in response to a PDP context usingthe second APN.

The SGSN sends the PDP context to the mobile station MS in message 4-11(Activate PDP Context Response). The PDP context is stored in the mobilestation MS, SGSN node and GGSN node. In the SGSN, each PDP context isstored together with the MM context.

In response to the message 4-10 the WAP server sends message 4-12 to themobile station MS. Message 4-12 contains information about freeservices, such as the possibility of depositing money in the account,possibility of changing prepaid subscription to postpaid subscription,and other services offered by the partners to the end users as free ofcharge services.

If the SCP finds out in step 4-5 that the balance has not reached thelimit (the preset minimum balance of the account), the SCP indicates inthe first preferred embodiment of the invention that the first APN isused. Then the message 4-7 indicates the use of the first APN and themessages 4-10 and 4-12 are not sent.

In some other embodiments where the GGSN is arranged to send the name ofthe used APN to the WAP server and the WAP server is arranged to informthe user of the allowed services, the messages 4-10 and 4-12 are sentregardless of which APN is used.

In some embodiments of the invention the messages 4-6 and/or 4-7 may notcontain the name of the second APN but an indication indicating thatonly services free of charge are allowed.

In some embodiments of the invention the message 4-7 contains only thename of the second APN, i.e. it does not indicate to the GGSN in any waythat only services free of charge are allowed. In these embodimentsmessages 4-10 and 4-12 are sent only if the GGSN is arranged to send thename of the used APN to the WAP server and the WAP server is arranged toinform the user of the allowed services.

In other embodiments of the invention message 4-10 triggering message4-12 is sent to the WAP server from the SCP or the SGSN, or, from a DHCPor a RADIUS server. The DHCP or the RADIUS server may receive theinformation triggering the message 4-10 during the PDP contextactivation, for example, when the GGSN requests the DHCP server toallocate a PDP address to the user or the RADIUS server to authenticatethe user.

In the second preferred embodiment of the invention the SCP does notperform the checking in point 4-5 since the HLR delivers the APN to beused with this PDP context. The SCP responds to message 4-4 by sendingcharging information and/or some related information in message 4-6, butthe message 4-6 does not contain the name of the APN nor an explicitindication which APN is to be used.

FIG. 5 illustrates the depositing service in the first preferred,embodiment of the invention. In the first preferred embodiment of theinvention the depositing service is a service located in the WAP server.For the sake of clarity it is assumed that there is an interface betweenthe depositing service and the SMP maintaining the prepaid accounts.

The mobile station MS sends message 5-1 to the WAP server, whichindicates that the user of the mobile station wants to deposit money inthe account of the subscription. The depositing service needsauthenticated access so that the operator can be sure who is depositing(and in group prepaid subscriptions it is also checked whether he hasthe right to deposit) and the one depositing can not deny this moneyadding. Since during the PDP context activation the mobile station (moreprecisely the SIM card) is authenticated by means of GSM procedures andthe user is optionally authenticated with a password, the WAP server cantrust the information received from the GPRS system. The WAP serverrequests user identification information from the GGSN in message 5-2.The GGSN obtains the user identification information from the PDPcontext the mobile station MS used when it sent message 5-1, and sendsthe user identification information to the WAP server in message 5-3.The user identification information is for example IMSI, or the phonenumber of the mobile station MSISDN.

After receiving message 5-3, the WAP server checks in point 5-4 whetherthe user is allowed to deposit. For example, a prepaid groupsubscription is a subscription where subscribers belonging to a groupshare one common prepaid subscription account, but only some of themembers are allowed to deposit.

If the user is not allowed to deposit, the WAP server sends message 5-5to the user informing him that he is not allowed to deposit.

If the user is allowed to deposit, the WAP server starts the actualdepositing service in point 5-6. Depositing service can be based on theknown (and authenticated) identity of the user, and an agreement betweenthe user and the operator on how to transfer money (based on the creditcard number, for example). Since the actual depositing service bears nosignificance to the invention, it is not described here in more detail.

After depositing the balance of the account will again exceed the limitand during the next PDP context activation the MS is connected to itsfirst set of services.

In the second preferred embodiment of the invention the WAP serveracknowledges the depositing to the SCP and in response to thisacknowledgement the SCP instructs the HLR to change the allowed APN tothe first APN. This triggers the deactivation and reactivation of thePDP context as described earlier.

In some other embodiments of the invention the WAP server may receivethe identity of the subscriber (message 5-3) from some other server thanthe GGSN, such as a DNS server, a RADIUS server, a DHCP server, anotherWAP server or a policy server. In these embodiments of the invention theWAP server requests user identification information from the said otherserver in message 5-2. The said other server has obtained the identityof the user using a given PDP address from the GGSN during the PDPcontext activation, and thus the said other server can obtain the useridentification information from its database and send it to the WAPserver in message 5-3.

In some other embodiments of the invention the WAP server may receivethe identity of the subscriber during the PDP context activation (e.g.in message 4-10 of FIG. 4) from the GGSN. The WAP server then keeps therelation between the PDP address and the user identity in its memory andmessages 5-2 and 5-3 are not needed.

The steps, signalling messages and points shown in FIGS. 2, 3, 4 and 5are not in absolute chronological order and they can be carried out in adifferent order from the given one. Other signalling messages can betransmitted and/or other functions can also be carried out between thesteps and/or the messages and/or points. The signalling messages areonly examples and may comprise several separate messages fortransmitting the same information. In addition, the messages may alsocomprise other information. Furthermore, the messages may be nameddifferently from the above-mentioned messages.

Although the invention has been described above assuming that thedifferent sets of services are provided via different WAP servers, it isalso possible to provide the different sets of services via one WAPserver by indicating to the WAP server which services are allowed. Theindication can be provided in many ways, for example:

1) The GGSN sends the indication indicating the allowed services to theWAP server when the MS activates its PDP context. This indication ispreferably an APN and it is sent to the WAP server with the RADIUSprotocol, for example.

2) Either the GGSN, the SGSN or the SCP sends the indication to anotherserver (not the WAP server) when the MS activates its PDP context.Before delivering a requested service, the WAP server checks from theother server whether the MS is allowed to access the requested service.One example of another servers is the RADIUS server.

3) Before delivering a requested service, the WAP server checks fromanother server whether the MS is allowed to access the requestedservice.

4) The GGSN sends an implicit indication indicating the allowed servicesto the WAP server when the MS activates its PDP context. The implicitindication is preferably the PDP address which the MS uses. Thisimplementation utilizes the fact that the PDP address corresponds to theAPN and the APN can force the PDP address to belong to a certain rangeof addresses. In this implementation the WAP server has a preconfiguredrange of PDP addresses linked to corresponding service access rights.Thus the WAP server can deduce from the PDP address used by the MS whichservices are allowed.

Although the invention has been described above in connection with WAPservers, it is obvious to one skilled in the art that the invention canbe implemented with any other application server, such as an imode,server and a web server.

Although the invention has been described above in connection withdifferent APNs defining different sets of services, it is obvious to oneskilled in the art that the invention can be implemented with any otherparameter or service used for service access authorisation. One exampleis call barring. Another example is maintenance of information onscreening policies defined for different sets of services. Also, a rangeof allowed addresses can be defined for each set of services or to a setof services. One can also define the allowed services with the QoSparameter. The QoS parameter may either allow or not allow a real-timeservice, for example. When a real-time service is not allowed, servicesallowing e.g. realtime video download or voice over IP (VoIP) can not beused. Different parameters and services can also be combined to define aset of services.

Although the invention has been described above in connection with theintelligent network IN and the SCP, it is obvious to one skilled in theart that the invention can be implemented with a non-IN based solution.One example is a prepaid server acting like the SCP in the secondpreferred embodiment of the invention. The prepaid server may receivecharging records from the SGSN and/or the GGSN in real time (e.g. basedon charging characteristics indicating a prepaid subscription insubscription information). The prepaid server maintains the balance ofthe account, and when the balance reaches one predefined limit, itinstructs the HLR (like the SCP in FIG. 3).

Although the invention has been described above in connection with aprepaid subscription, it is obvious to one skilled in the art that theinvention can also be applied in connection with a postpaid subscriptionwith a limited bill. As stated earlier, the latter subscription differsfrom the prepaid subscription in that the predefined limit (the maximumallowed amount to be billed) is reached when the balance equals thelimit. So, if the balance is below the limit, the charged services areallowed. It is also possible to use a service similar to the depositingservice described in FIG. 5, to raise the value of the predefined limit.

It is to be understood that the above description and the figuresrelated to it are only intended to illustrate the present invention. Itwill be obvious to a person skilled in the art that the invention may bemodified in different ways without deviating from the scope and spiritof the invention disclosed in the appended claims.

1. A method comprising: determining services accessible via asubscription having an account and at least a first limit in acommunication system; defining at least a first set of services and asecond set of services to be used with the subscription, each of saidfirst and said second set of services defining services accessible viathe subscription; defining a first access point name for the first setof services; defining a second access point name for the second set ofservices; comparing a balance of the account with the first limit;selecting, in response to the result of the comparison, a range ofallowed IP addresses to be used for accessing one of said first andsecond set of services, wherein the first range of allowed IP addressesis selected when the balance of the account does not reach the firstlimit; and the second range of allowed IP addresses is selected when thebalance reaches the first limit.
 2. A method as claimed in claim 1, thecommunication system comprising a firewall, the method furthercomprising defining accessible services via a set of services bydefining at least a firewall configuration for the set of services.
 3. Amethod as claimed in claim 1, the method further comprising using in thecommunication system access point names to define where and how toconnect the user of the subscription; and linking each defined range ofallowed IP addresses to an access point name.
 4. A method as claimed inclaim 1, the method further comprising indicating a particular set ofservices which is to be used by charging characteristics to be applied.5. A method as claimed in claim 1, the second set of services comprisingfree of charge services.
 6. A method as claimed in claim 1, the methodfurther comprising informing the user of the subscription of theservices accessible via the second set of services in response to usingthe second set of services.
 7. A method as claimed in claim 1, wherein:the subscription is a postpaid subscription; the first limit is themaximum allowed amount of the bill; and the balance of the accountindicates the amount of the bill to be charged from the subscription. 8.A method as claimed in claim 1, wherein: the subscription is a prepaidsubscription; the first limit is the preset minimum value for theaccount; and the balance of the account indicates the amount of moneythe subscriber still has in use.
 9. A method as claimed in claim 8,wherein at least the second set of services comprises a depositingservice.
 10. A method as claimed in claim 9, wherein the depositingservice utilizes authentication of the communication system whenauthenticating the one who wants to deposit.
 11. A method as claimed inclaim 1, wherein the subscription further has subscription informationmaintained in the communication system; the method further comprisingadding to the subscription information at least one of the first rangeof allowed IP addresses and the second range of allowed IP addresses.12. A communication system comprising: a first node configured tomonitor a balance of an account; a memory configured to storedefinitions of at least a first set of services associated with a firstaccess point name and a second set of services associated with a secondaccess point name to be used with a subscription, each set of servicesdefining services accessible via the subscription, wherein the firstnode compares the balance of the account with the first limit, andselects, in response to the result of the comparison, a range of allowedIP addresses to be used with this connection for accessing one of saidfirst and second set of services, wherein the first range of allowed IPaddresses is selected when the balance of the account does not reach thefirst limit and the second range of allowed IP addresses is selectedwhen the balance reaches the first limit; the communication system beingconfigured to provide the subscription with the account and at least afirst limit.
 13. An apparatus comprising: a processor; and memoryincluding computer program code; the memory and the computer programcode configured to, with the processor, cause the apparatus at least toperform: associating a first range of allowed IP addresses with a firstset of services, and a second range of allowed IP addresses with asecond set of services, both sets of services defining servicesaccessible via the subscription; comparing a balance of an account witha first limit; selecting, in response to the result of the comparison, arange of allowed IP addresses to be used for accessing one of said firstand second set of services, wherein the first range of allowed IPaddresses is selected when the balance of the account does not reach thefirst limit and the second range of allowed IP addresses is selectedwhen the balance reaches the first limit; the apparatus being in acommunication system configured to provide the subscription with theaccount and at least a first limit, the apparatus being furtherconfigured to monitor the balance of the account.
 14. An apparatuscomprising: a processor; and memory including computer program code; thememory and the computer program code configured to, with the processor,cause the apparatus at least to perform: associating a first range ofallowed IP addresses with a first set of services and a second range ofallowed IP addresses with the second set of services, both sets ofservices defining services accessible via a subscription; communicatingwith a second apparatus; comparing a balance of an account with a firstlimit; selecting in response to the result of the comparison, range ofallowed IP addresses to be used for accessing one of said first andsecond set of services, wherein the first range of allowed IP addressesis selected when the balance of the account does not reach the firstlimit and the second range of allowed IP addresses is selected when thebalance reaches the first limit, and indicating to the second apparatusthe selected range of allowed IP addresses; the apparatus being in acommunication system configured to provide the subscription with theaccount and at least a first limit, the apparatus being furtherconfigured to monitor the balance of the account.
 15. A apparatus asclaimed in claim 14, wherein the apparatus is configured to indicate theselected range of allowed IP addresses in response to the balancereaching the limit and in response to the balance not any more reachingthe limit and in response to the balance not any more reaching thelimit.
 16. An apparatus comprising: a processor; and memory includingcomputer program code; the memory and the computer program codeconfigured to, with the processor, cause the apparatus at least toperform: storing a first range of allowed IP addresses used in acommunication system to define where and how to connect a user of asubscription; providing access to a first set of services accessible tothe subscription using the first range of allowed IP addresses;receiving from the communication system a second range of allowed IPaddresses indicating the use of a second set of services instead of thefirst set of services for the for the subscription, and, in response toreceiving the second range of allowed IP addresses, modifying the storedfirst range of allowed IP addresses with the received second range ofallowed IP addresses, and providing access only to services included inthe indicated second set of services accessible to the subscriptionusing the second range of allowed IP addresses; the apparatus being in acommunication system configured to provide the subscription.
 17. Anapparatus as claimed in claim 16, wherein the apparatus is configured,in response to receiving the indication, to inform the user of thesubscription of the services accessible via the indicated certain set ofservices.
 18. A apparatus as claimed in claim 16, wherein the apparatusis an application server.
 19. A processor comprising: memory includingcomputer program code; the memory and the computer program codeconfigured to cause an apparatus in a communication system at least toperform: providing a subscription with an account and at least a firstlimit; associating a first access range of allowed IP addresses with afirst set of services, and a second range of allowed IP addresses with asecond set of services, both sets of services defining servicesaccessible via the subscription; monitoring a balance of the account;comparing a balance with the first limit; selecting, in response to theresult of the comparison, a range of allowed IP addresses to be used foraccessing one of said first and second set of services in response tothe result of the comparison, wherein the first range of allowed IP isselected when the balance of the account does not reach the first limitand the second range of allowed IP addresses is selected when thebalance reaches the first limit.
 20. A processor comprising: memoryincluding computer program code; the memory and the computer programcode configured to cause an apparatus in a communication system at leastto perform: providing a subscription with an account and at least afirst limit; associating a first range of allowed IP addresses with afirst set of services, and a second range of allowed IP addresses with asecond set of services, both sets of services defining servicesaccessible via the subscription; communicating with a second apparatus;comparing a balance with the first limit; selecting, in response to theresult of the comparison, a range of allowed IP addresses to be used foraccessing one of said first and second set of services, wherein thefirst range of allowed IP addresses is selected when the balance of theaccount does not reach the first limit and the second range of allowedIP addresses is selected when the balance reaches the first limit; andindicating, in a form of the selected range of allowed IP addresses tothe second apparatus, which set of services from among at least twodifferent sets of services defined for the subscription is the allowedset of services on the basis of said comparison.
 21. A processor asclaimed in claim 20, further comprising program code configuring theapparatus to indicate the allowed set of services in response to thebalance reaching the limit and in response to the balance not any morereaching the limit.
 22. A processor comprising: memory includingcomputer program code; the memory and the computer program codeconfigured to cause an apparatus in a communication system at least toperform: providing a subscription, storing a first range of allowed IPaddresses used in the communication system to define where and how toconnect a user of the subscription; providing access to a first set ofservices accessible to the subscription using the first range of allowedIP addresses; receiving from a communication system a second range ofallowed IP addresses indicating the use of a second set of servicesinstead of the first set of services for the subscription; and, inresponse to receiving the indication, to modify the stored first rangeof allowed IP addresses with the received second range of allowed IPaddresses, and provide access only to services included in the indicatedsecond set of services using the second range of allowed IP addresses.23. A processor as claimed in claim 22, further comprising program codeconfiguring the apparatus to, in response to receiving the indication,inform the user of the subscription of the services accessible via theindicated certain set of services.
 24. A computer readable storagemedium encoding and storing a computer program of instructions thereinfor executing a computer process for determining services accessible viaa subscription having an account and at least a first limit in acommunication system, the process comprising: defining at least a firstset of services and a second set of services to be used with thesubscription, each set of services defining services accessible via thesubscription; defining a first range of allowed IP addresses for thefirst set of services; and defining a second range of allowed IPaddresses for the second set of services; comparing a balance of theaccount with the first limit; selecting, in response to the result ofthe comparison, a range of allowed IP addresses to be used for accessingone of said first and second set of services, wherein the first range ofallowed IP addresses is selected when the balance of the account doesnot reach the first limit; and the second range of allowed IP addressesis selected when the balance reaches the first limit.